Merge branch 'ipv6-misc-changes-in-output-path'

Eric Dumazet says:

====================
ipv6: misc changes in output path

Small optimizations mostly in ip6_xmit() path.

TX performance increases by about 3 %.

Patches 5-7: add dst4_mtu() and dst6_mtu() to save space.

Last patch colocates inet6_cork in inet_cork_full.

This series reduces kernel size by 494 bytes on x86_64:

scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 4/2 grow/shrink: 9/23 up/down: 665/-1159 (-494)
Function                                     old     new   delta
ip6_finish_output_gso_slowpath_drop            -     197    +197
ip6_xmit                                    1452    1595    +143
do_ipv6_getsockopt                          2855    2950     +95
kzalloc_noprof                                 -      55     +55
ip4ip6_err                                   918     955     +37
__icmp_send                                 1499    1532     +33
do_ip_getsockopt                            2573    2605     +32
__ip6_append_data                           4109    4137     +28
__pfx_kzalloc_noprof                           -      16     +16
__pfx_ip6_finish_output_gso_slowpath_drop       -      16     +16
ipmr_prepare_xmit                           1232    1238      +6
ip6_forward                                 1905    1909      +4
ip6_cork_release                             108     111      +3
ipv6_push_nfrag_opts                         489     486      -3
ipv6_push_frag_opts                           90      87      -3
ip6_finish_output2                          1446    1437      -9
ip6_tnl_xmit                                2639    2627     -12
ip6_default_advmss                           176     160     -16
__ip6_rt_update_pmtu                        1087    1071     -16
tcp_v6_syn_recv_sock                        1715    1696     -19
tcp_v4_syn_recv_sock                        1107    1088     -19
__ip_make_skb                               1339    1320     -19
ip_setup_cork                                406     385     -21
ip6_setup_cork                               732     710     -22
rawv6_push_pending_frames                    581     556     -25
ip6_push_pending_frames                      184     157     -27
udpv6_splice_eof                             203     170     -33
ip6_flush_pending_frames                     220     183     -37
ip6_append_data                              349     312     -37
udp_v6_push_pending_frames                   155     115     -40
sit_tunnel_xmit                             1957    1914     -43
__pfx_dst_mtu                                 64       -     -64
tcp_v4_mtu_reduced                           289     220     -69
tcp_v6_mtu_reduced                           209     139     -70
ip6_make_skb                                 574     484     -90
ip6_finish_output                            827     697    -130
dst_mtu                                      160       -    -160
fib6_nh_mtu_change                           511     336    -175
Total: Before=22584400, After=22583906, chg -0.00%
====================

Link: https://patch.msgid.link/20260130210303.3888261-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

5 files changed, 29 insertions, 17 deletions

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 7294e4e89b79..20aae8357dd1 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -205,13 +205,6 @@ struct ipv6_mc_socklist;
 struct ipv6_ac_socklist;
 struct ipv6_fl_socklist;
 
-struct inet6_cork {
-	struct ipv6_txoptions *opt;
-	u8 hop_limit;
-	u8 tclass;
-	u8 dontfrag:1;
-};
-
 /* struct ipv6_pinfo - ipv6 private area */
 struct ipv6_pinfo {
 	/* Used in tx path (inet6_csk_route_socket(), ip6_xmit()) */
@@ -267,7 +260,6 @@ struct ipv6_pinfo {
 
 	struct sk_buff		*pktoptions;
 	struct sk_buff		*rxpmtu;
-	struct inet6_cork	cork;
 
 	struct ipv6_mc_socklist	__rcu *ipv6_mc_list;
 	struct ipv6_ac_socklist	*ipv6_ac_list;
diff --git a/include/net/dst.h b/include/net/dst.h
index f8aa1239b4db..307073eae7f8 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -219,6 +219,12 @@ static inline u32 dst_mtu(const struct dst_entry *dst)
 	return INDIRECT_CALL_INET(dst->ops->mtu, ip6_mtu, ipv4_mtu, dst);
 }
 
+/* Variant of dst_mtu() for IPv4 users. */
+static inline u32 dst4_mtu(const struct dst_entry *dst)
+{
+	return INDIRECT_CALL_1(dst->ops->mtu, ipv4_mtu, dst);
+}
+
 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 {
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 903b2263ec80..7cdcbed3e5cb 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -159,6 +159,13 @@ static inline bool inet_sk_bound_dev_eq(const struct net *net,
 #endif
 }
 
+struct inet6_cork {
+	struct ipv6_txoptions *opt;
+	u8 hop_limit;
+	u8 tclass;
+	u8 dontfrag:1;
+};
+
 struct inet_cork {
 	unsigned int		flags;
 	__be32			addr;
@@ -179,6 +186,9 @@ struct inet_cork {
 struct inet_cork_full {
 	struct inet_cork	base;
 	struct flowi		fl;
+#if IS_ENABLED(CONFIG_IPV6)
+	struct inet6_cork	base6;
+#endif
 };
 
 struct ip_mc_socklist;
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 7c5512baa4b2..a55f9bf95fe3 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -266,6 +266,12 @@ static inline bool ipv6_anycast_destination(const struct dst_entry *dst,
 int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 		 int (*output)(struct net *, struct sock *, struct sk_buff *));
 
+/* Variant of dst_mtu() for IPv6 users */
+static inline u32 dst6_mtu(const struct dst_entry *dst)
+{
+	return INDIRECT_CALL_1(dst->ops->mtu, ip6_mtu, dst);
+}
+
 static inline unsigned int ip6_skb_dst_mtu(const struct sk_buff *skb)
 {
 	const struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ?
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index cf2203ff2bfd..c27b9d7aeb7c 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -1107,8 +1107,7 @@ void ip6_flush_pending_frames(struct sock *sk);
 int ip6_send_skb(struct sk_buff *skb);
 
 struct sk_buff *__ip6_make_skb(struct sock *sk, struct sk_buff_head *queue,
-			       struct inet_cork_full *cork,
-			       struct inet6_cork *v6_cork);
+			       struct inet_cork_full *cork);
 struct sk_buff *ip6_make_skb(struct sock *sk,
 			     int getfrag(void *from, char *to, int offset,
 					 int len, int odd, struct sk_buff *skb),
@@ -1119,8 +1118,7 @@ struct sk_buff *ip6_make_skb(struct sock *sk,
 
 static inline struct sk_buff *ip6_finish_skb(struct sock *sk)
 {
-	return __ip6_make_skb(sk, &sk->sk_write_queue, &inet_sk(sk)->cork,
-			      &inet6_sk(sk)->cork);
+	return __ip6_make_skb(sk, &sk->sk_write_queue, &inet_sk(sk)->cork);
 }
 
 int ip6_dst_lookup(struct net *net, struct sock *sk, struct dst_entry **dst,
@@ -1151,11 +1149,11 @@ int ip6_local_out(struct net *net, struct sock *sk, struct sk_buff *skb);
  *	Extension header (options) processing
  */
 
-void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
-			  u8 *proto, struct in6_addr **daddr_p,
-			  struct in6_addr *saddr);
-void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
-			 u8 *proto);
+u8 ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
+			u8 proto, struct in6_addr **daddr_p,
+			struct in6_addr *saddr);
+u8 ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
+		       u8 proto);
 
 int ipv6_skip_exthdr(const struct sk_buff *, int start, u8 *nexthdrp,
 		     __be16 *frag_offp);